Prolactin-adjusted ACTH Ratio in Predicting Lateralization of ACTH Source During Simultaneous Bilateral Inferior Petrosal Sinus Sampling in Patients with Cushing's Disease.

Abstract

Introduction:Prolactin-adjusted adrenocorticotropic hormone (ACTH) ratio is used to improve the diagnostic accuracy of bilateral inferior petrosal sinus sampling (BIPSS) for lateralization of pituitary adenoma.Objective:To study the use of prolactin for successful catheterization during BIPSS, the role of prolactin-normalized ACTH ratio for confirmation of Cushing's disease (CD) and prolactin-adjusted ACTH ratio in predicting the lateralization.Patients and Methods:BIPSS was done in patients with CD; prolactin-adjusted ACTH ratio was compared with intersinus ACTH ratio, magnetic resonance imaging, and intraoperative findings for localization of pituitary adenoma. Histopathology was taken as “gold standard” for the diagnosis of CD.Results:Eight patients underwent BIPSS. All the patients underwent transsphenoidal surgery. All these patients had proper venous sampling during BIPSS as determined by inferior petrosal sinus (IPS):Peripheral prolactin ratio of ≥1.8. Prolactin-normalized ACTH ratio of ≥1.3 was achieved in all the eight patients, which was consistent with the diagnosis of CD. Concordance of intersinus ACTH ratio ≥1.4 with the intraoperative findings was found in five of eight (62.5%) patients depicting correct lateralization. Concordance of prolactin-adjusted ACTH ratio with intraoperative findings was found in four of eight (50%) patients. Seven of eight patients had concordance of intersinus ACTH ratio with prolactin-adjusted ACTH ratio.Conclusion:Prolactin is a useful marker for successful catheterization, confirming the diagnosis of CD during BIPSS, and prolactin-adjusted ACTH ratio does not add to the accuracy of lateralization of pituitary adenoma compared with intersinus ACTH ratio.